A ligand-free hydrogel as a visual fluorescence sensor for detection of rare-earth ions

In this work, a ligand-free luminescent hydrogel is used as a visual ratiometric fluorescence sensor to detect rareearth (RE) ions for the first time. This hydrogel is easy to be prepared, environmentally friendly, and has high luminescent efficiency. It is found that the fluorescence intensity and emission color of the hydrogel immediately change significantly when solution of active RE3+ 3 + ions is added without any treatment. According to the linear relationship between the fluorescence intensity ratio and the concentration of RE3+ 3 + solutions, the detection limit is calculated to be as low as 0.94 mu M. The detection of RE ions has strong anti-interference to other ions. Therefore, this sensor can be used for preliminary field exploration of RE ores and detection of waste containing small amounts of RE ions.